The invention relates generally to implementation of services in a telecommunications network, particularly an intelligent network. The service may be any service produced in the network for a network user or another object.
The rapid evolvement of the telecommunications field has afforded operators the capability of providing many different types of services to users. A network architecture that provides advanced services is called an intelligent network. The common abbreviation for intelligent network is IN.
The functional architecture of an intelligent network is shown in FIG. 1 where the functional entities of the network are shown as ovals. This architecture is described briefly below, because the invention will be described hereinafter with reference to the intelligent network environment.
The access of the end user (subscriber) to the network is handled by the CCAF (Call Control Agent Function). The access to the IN services is implemented by making additions to existing digital exchanges. This is done by using the basic call state model BCSM which describes the existing functionality used to process a call between two users. The BCSM is a high level state automaton description of the call control functions CCF required for establishing and maintaining a connection route between users. Functionality is added to this state model by using the service switching function SSF (cf. the partial overlap of the entities CCF and SSF in FIG. 1) so that it is possible to decide when it is necessary to call the services of the intelligent network (the IN services). After these IN services have been called, the service control function SCF that contains the service logic for the intelligent network handles the service-related processing (of the call attempt). The service switching function SSF thereby connects the call control function CCF to the service control function SCF and allows the service control function SCF to control the call control function CCF. For example, SCF can request that the SSF/CCF perform specific call or connection functions, for example charging or routing operations. The SCF can also send requests to the service data function SDF which handles the access to the service-related data and network data of the intelligent network. The SCF can thus for example request the SDF to retrieve specific service-related data or update this data.
The functions described above are further complemented by the specialized resources function SRF which provides the special functions required for implementing some of the services provided by the intelligent network. Examples of these services are protocol conversions, speech recognition, voice mail, etc. The SCF can, for example, request the SSF/CCF functions to first establish a connection between the end users and SRF and then it can request the SRF to give voice announcements to the end users.
Other functional entities of the intelligent network are various functions that relate to control, such as the SCEF (Service Creation Environment Function), SMF (Service Management Function), and SMAF (Service Management Access Function). The SMF includes, among other things, service control, the SMAF provides the connection to the SMF, and the SCEF makes it possible to specify, develop, test and feed IN services via the SMF to the SCF. Because these functions only relate to the operation of the network operator, they are not shown in FIG. 1.
The role of the functional entities described in FIG. 1 as relating to the IN services will be briefly described below. The CCAF receives the service request given by the calling party. The service request usually consists of lifting the receiver and/or a series of digits dialled by the calling party. The CCAF further transmits the service request to the CCF/SSF for processing. The call control function CCF does not have the service data but it has been programmed to recognize the need of a service request. The CCF interrupts the call setup for a moment and notifies the service switching function SSF about the state of the call. The task of the SSF is, using predefined criteria, to interpret the service request and thus determine whether the request is a service request related to the IN services. If this is the case, the SSF composes a standardized IN service request and sends the request to the SCF along with information about the state of the service request. The SCF receives the request and decodes it. After that it cooperates with the SSF/CCF, SRF, and SDF to provide the requested service to the end user.
The physical level architecture of the intelligent network describes how the functional entities described above are located in the physical entities of the network. The physical architecture of the intelligent network is illustrated in FIG. 2, where the physical entities are-described as rectangles or circles and functional entities as ovals. The signalling connections are described by dashed lines and the actual transport which is for example speech, by continuous lines. The optional functional entities are denoted with dashed line. The signalling network shown in the Figure is a network according to SS7 (Signalling System Number 7 is a well-known signalling system described in the CCITT (nowadays ITU-T) blue book Specifications of Signalling System No. 7, Melbourne 1988).
The subscriber equipment SE which can include, for example, a telephone, computer, or telefax, are connected either directly to a service switching point SSP or to a network access point NAP.
The service switching point SSP provides the user with access to the network and handles all necessary selection functions. The SSP can also detect any IN service requests. Functionally, the SSP includes the call control and service selection functions.
The network access point NAP is a traditional telephone exchange that includes the call control function CCF, for example, the Applicants"" DX 220 exchange which can differentiate calls that require IN services from traditional calls and route the calls that require IN services to the appropriate SSP.
The service control point SCP includes the service logic programs SLP that are used to produce the IN services. The shorter term service program will also be used for service logic programs in the following.
The service data point SDP is a database containing customer and network data which is used by the service programs of the SCP to produce tailored services. The SCP can use SDP services directly via the signalling or data network.
The intelligent peripheral IP provides special services, such as announcements and voice and multiple choice recognition.
The service switching and control point SSCP consists of an SCP and SSP located in the same network element (in other words, if the SSP network element shown in the drawing contains both an SCF and an SSF entity, the network element in question is an SSCP).
The tasks of a service management system SMP include the management of the database (SDP), network monitoring and testing, and collecting network data. It can connect to all other physical entities.
The service creation environment point SCEP is used for specifying, developing and testing the IN services, and for entering the services in SMP.
The service adjunct AD is functionally equivalent to the service control point SCP, but it is directly connected to SSP with a fast data connection (for example, with an ISDN 30B+D connection) instead of via the common channel signalling network SS7.
The service node SN can control the IN services and perform data transfers with users. It communicates directly with one or more SSPs.
The service management access point SMAP is a physical entity which provides certain users with a connection to SMP.
The above is a brief description of the intelligent network as a background to the description of the method according to the invention. The interested reader can get a more detailed description of the intelligent network in, for example, ITU-T specifications Q.121X or in the AIN specifications of Bellcore.
It should be possible to provide IN-based services to subscribers in fixed or mobile networks in a way enabling provision of tailored service in such a way that a specific subscriber-associated combination of service features can be offered to each individual subscriber. As stated previously, provisioning of a service is initiated in such a way that the SSF sends to the SCF a standard IN service request. The service request can be sent at certain stages of the call setup. The international standards, however, specify only one identifier for the service request sent by the SSF wherewith the desired service logic can be selected in the SCP. This identifier is called the service key.
The generally known technique for providing tailored services is such that the final service logic program SLP is selected in the SCP by means of the service key value, in which case more than one values can point to the same service logic program or there may be a dedicated service logic program for each service key value. When it is desired to add services, a new version of the existing service logic program into which more service features are encoded is produced. The new version is indicated with a new service key value. The subservices, for which the English term service feature is employed in the international standards, are termed features in the present context.
The drawback of such a solution is that as services and features contained in them increase, the service programs are rendered highly complex and their number increases. When such extensive programs, of which furthermore different versions exist, must be located in several network elements of the network, also the maintenance of the network becomes complicated.
It is an object of the invention to bring about an improvement to the above situation and to provide a solution wherewith the adding of new services and maintenance of services provided by the network is as simple and flexible as possible.
This object is achieved with the method in accordance with the invention, which is defined in the independent claim.
The idea of the invention is to use keys identifying the features and to construct the service programs from feature-related modules in such a way that by means of a given feature key, the part of the service program corresponding to said key is executed, and the entire service is provided by concatenating the desired feature modules in succession by means of feature keys. The SCP network element stores in connection with each feature information on which service program is capable of executing said feature, and by means of the service key arriving in the service request message, the set of desired features is defined, and thus the service can be provided by executing the parts of one or more service programs which correspond to said features in a given consecutive order.
On account of the solution in accordance with the invention, the program code required by the features can be placed very freely in one or more service logic programs. One service logic program preferably contains the code required to execute several features, even though it can contain the code required by one feature only. The services corresponding to some service key values can be located in a given SCP network element, and the services corresponding to some other values in another SCP network element. By dividing the features of the service e.g. among two different SCP network elements, no service logic program that is too extensive in view of the network resources or performance need to be located in either of the network elements. Thus, no SCP network element need contain all possible services or features, even though they are available to all subscribers.
With regard to network maintenance, the solution of the invention also enables a simple way of offering new services comprised of subscriber-specific feature combinations.